import os


def main():
    type_set = set()
    top = os.getcwd()
    for root, dirs, files in os.walk(top):
        for file in files:
            if "." in file:
                type_set.add(file[file.rindex("."):])
            else:
                type_set.add("no_posfix")
    for v in sorted(type_set):
        print(v)


if __name__ == '__main__':
    main()
